1. Field of the Invention
This invention relates to thin cemented refractory metal carbide articles having at least two uneroded formed surfaces, and also relates to thin flexible unsintered articles of carbide and cementing metal particles suspended in an organic matrix and to a tape casting process for producing such sintered and unsintered articles.
2. Prior Art
Cemented refractory metal carbides are noted for their hardness and wear resistance and have wide application as wear resistant surfaces or components thereof. Such surfaces are sometimes formed by coating, for example by flame spraying a powder onto a substrate. In many applications, however, the wear surface is not amenable to formation by coating, for example where it is an internal surface of a pump, pipe, conveyer, reactor, etc. In these instances, thin carbide wear resistant surfaces have been formed by machining unsintered consolidated powders produced by extrusion or pressing, followed by sintering and finishing. Such operations tend to be time consuming and wastive of material, not only through erosion of the surfaces by machining, but also through breakage of the fragile unsintered parts. Furthermore, in some instances this fragility together with the complexity of the final desired shape requires machining of the sintered carbide article, which is extremely difficult due to the inherent hardness of the carbide particles.
In the U.S. Patent application Ser. No. 418,397, filed Nov. 23, 1973, now abandoned and assigned to the present assignee, there is described a technique for producing thin hard sintered articles such as cemented carbides without appreciable machining, the technique involving tape casting thin sheets from a slurry, and forming and sintering these sheets.
While the above technique is felt to represent a significant advance in the art, enabling convenient and relatively cheap fabrication of thin hard articles, nevertheless the strength and wear resistance of these articles is sometimes inadequate for the most demanding applications.
It is therefore felt that further improving the strength and wear resistant properties of these articles would be a further advance in the art.